Sleep disturbances, including repetitive nightmares and insomnia, are central and long-lasting aspects of Post-Traumatic Stress Disorder (PTSD). This study utilized a questionnaire to compare sleep disturbance in Vietnam War combat veterans having PTSD with non-PTSD patients having insomnia without other PTSD symptoms. The PTSD group reported symptoms of anxiety, agitation and concurrent body movement which were associated with insomnia. Nightmares of this group were more repetitive and more disruptive of a return to sleep than the non-PTSD insomnia group. The PTSD group also reported more fatigue during daytime functioning and more anxiety during waking hours than the non-PTSD insomnia group.